title: DNase 2 is the main DNA-degrading enzyme of the stratum corneum.
abstract: The cornified layer, the stratum corneum, of the epidermis is an efficient barrier to the passage of genetic material, i.e. nucleic acids. It contains enzymes that degrade RNA and DNA which originate from either the living part of the epidermis or from infectious agents of the environment. However, the molecular identities of these nucleases are only incompletely known at present. Here we performed biochemical and genetic experiments to determine the main DNase activity of the stratum corneum. DNA degradation assays and zymographic analyses identified the acid endonucleases L-DNase II, which is derived from serpinB1, and DNase 2 as candidate DNases of the cornified layer of the epidermis. siRNA-mediated knockdown of serpinB1 in human in vitro skin models and the investigation of mice deficient in serpinB1a demonstrated that serpinB1-derived L-DNase II is dispensable for epidermal DNase activity. By contrast, knockdown of DNase 2, also known as DNase 2a, reduced DNase activity in human in vitro skin models. Moreover, the genetic ablation of DNase 2a in the mouse was associated with the lack of acid DNase activity in the stratum corneum in vivo. The degradation of endogenous DNA in the course of cornification of keratinocytes was not impaired by the absence of DNase 2. Taken together, these data identify DNase 2 as the predominant DNase on the mammalian skin surface and indicate that its activity is primarily targeted to exogenous DNA.
authors.affiliation: Department of Dermatology, Medical University of Vienna, Vienna, Austria.
authors.forename: Heinz
authors.initials: H
authors.lastname: Fischer
authors.forename: Jennifer
authors.initials: J
authors.lastname: Scherz
authors.forename: Sandra
authors.initials: S
authors.lastname: Szabo
authors.forename: Michael
authors.initials: M
authors.lastname: Mildner
authors.forename: Charaf
authors.initials: C
authors.lastname: Benarafa
authors.forename: Alicia
authors.initials: A
authors.lastname: Torriglia
authors.forename: Erwin
authors.initials: E
authors.lastname: Tschachler
authors.forename: Leopold
authors.initials: L
authors.lastname: Eckhart
mesh_terms: D000818:Animals; D004247:DNA / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D004817:Epidermis / Q000201:enzymology*; D006801:Humans; D051379:Mice; D015843:Serpins / Q000378:metabolism; D017768:Skin, Artificial
chemical_list: C522950:Serpinb1a protein, mouse; D015843:Serpins; C075177:SERPINB1 protein, human; D004247:DNA; D004706:Endodeoxyribonucleases; C019329:deoxyribonuclease II